The present invention relates generally to a method for producing a semiconductor device using a fluorine containing carbon film.
In order to achieve high integration of a semiconductor device, it has been developed to provide devices, such as scale down of a pattern and multilayering of a circuit. As one of such devices, there is a technique for multilayering interconnection layers. In order to provide a multi layer metallization structure, a number n interconnection layer and a number (n+1) interconnection layer are connected to each other by means of a conductive layer, and a thin film called an interlayer insulator film is formed in a region other than the conductive layer.
As one of typical interlayer insulator films, there is a SiO2 film. In recent years, in order to more accelerate operation of a device, it has been required to reduce the relative dielectric constant of the interlayer insulator film, and the material of the interlayer insulator film has been examined. That is, the relative dielectric constant of SiO2 is about 4, and it has been diligently studied to dig up materials having a smaller relative dielectric constant than that of SiO2. As one of such materials, it has been studied to put SiOF having a relative dielectric constant of 3.5 into practice. The inventor has taken notice of a fluorine containing carbon film (for example, such as a fluorocarbon film) having a still smaller relative dielectric constant.
By the way, the fluorine containing carbon film has many unknown factors, and a method for producing the fluorine containing carbon film itself has been searched. For example, in conventional etching processes, the fluorine containing carbon film can not be etched with a CF gas, such as CF4, which is used as an etching gas for a SiO2 film, since the film itself to be etched is a CF material. Thus, the conventional processes can not be applied directly to the fluorine containing carbon film. Therefore, although the fluorine containing carbon film is suitable for an interlayer insulator film, there are many problems in order to put an interlayer insulator film of a fluorine containing carbon film into practice.
It is therefore a principal object of the present invention to eliminate problems in an etching process and to enable to etch a fluorine containing carbon film to put an interlayer insulator film of a fluorine containing carbon film into practice.
The first invention of the present application is characterized by the steps of: depositing an insulator film of a fluorine containing carbon film on an object to be treated; forming a pattern of a resist film on the insulator film; and removing the resist film while etching the insulator film by an oxide plasma. Specifically, this invention includes the following steps. When a predetermined recessed portion is formed on the insulator film by etching, the resist film may remain on the insulator film. The etch rate of the fluorine containing carbon film etched by the oxide plasma may be equal to the etch rate of the resist film etched by the oxide plasma.
The second invention of the present invention is characterized by the steps of: depositing an insulator film of a fluorine containing carbon film on an object to be treated; forming a pattern of a resist film on the insulator film; and producing a plasma of a treatment gas containing an oxygen plasma producing gas and a silane compound gas, and removing the resist film while etching the fluorine containing carbon film by the produced plasma.
The third invention of the present application is characterized by the steps of: depositing an insulator film of a fluorine containing carbon film on an object to be treated; depositing a protective coat resistant to an oxygen plasma, on the insulator film; forming a pattern of a resist film on the protective coat; etching the protective coat, which is exposed so as to correspond to the pattern of the resist film, to remove the protective coat; and removing the resist film while etching the fluorine containing carbon film by an oxygen plasma. In this case, the protective coat may be an insulator film or a conductive film.
The fourth invention of the present application is characterized by the steps of: depositing an insulator film of a fluorine containing carbon film on an object to be treated; depositing a titanium nitride film on the insulator film; forming a pattern of a resist film on the insulator film; etching the titanium nitride film, which is exposed so as to correspond to the pattern of the resist film, to remove the titanium nitride film; and removing the resist film while etching the fluorine containing carbon film by an oxygen plasma.
In the above cases, when a metal layer is formed below the fluorine containing carbon film, oxide on the metal layer is preferably removed by argon plasma after the fluorine containing carbon film is etched to expose the metal layer.